mp4a to ac3/mp2 ?

Hi,

I'd like to create a demo dvd with a lot of new trailers. I download them from apple in HD 720p and then reencode them with AviSynth and HCEnc. It works fine but I have a problem with the audio stream.
In their files, they use mp4a and I don't know how to convert it to a dvd format (ac3/mp2). At this time I can convert the stream in LPCM 2 channels with mplayer but this is a demo disc so I'm looking for 6 channels.

Thx.

 

ffmpeg and I'd definatly go with AC3 over mp2.

 

It doesn't seem to work or I don't know how to use it.
I tried to load the .mov file. I suppose I have to demux the audio and video from the file before using ffmpeg but how do I do that ?

Thx

 

libavformat has an mov demuxer, so there should be no need to demux before hand.

 

Errr, seems ffmpeg doesn't like the 5.1 aac in quicktime trailers. Don't know why Apple can't just use mp4 as a container. You could try demuxing.

edit: looks like ffmpeg might have issues with all 6 channel aac.

mplayer should be outputting 6 channel pcm audio though which ffmpeg can convert or you could use mencoder, then demux the audio. mencoder.exe -ovc frameno -channels 6 -oac lavc -lavcopts acodec=ac3:abitrate=384 input.mov -o output.avi

Unlike ffmpeg though I don't think there is any way to directly output an audio only stream.

 

My mplayer doesn't play 5.1 files, it detects only 2ch...

 

Default is 2 channels. If you have more than two speakers then you should have set in your config. channels=6. mencoder doesn't read the config file so you need to specify. You can do the same with mplayer to. Just that it is easier to set default options in the config (fullscreen, subtitle font, menu, etc.).

 

Yep, but when I use channels=6 I've a problem with the sound which seems to play very very slowly. It's the same if I use channels=4.

Could you try on your side if it works ? (I'm under windows xp)

 

Works fine here. I've had channels=6 in my config file for ages. -channels 6 worked fine to convert a mov trailer earlier to. Trailer in question was cars-tsr4_h720p.mov

mplayer/mencoder build used was from the 10th.

 

If you're under windows, can you tell me where do you find so updated builds ? The one on the official website is "MPlayer dev-CVS-050928-16:38-3.4.2"

Thx

 

I compile them myself.
You can find my builds at: http://ffdshow.faireal.net/mirror/mplayer/
or alternative builds at: http://oss.netfarm.it/mplayer-win32.php

You are also of course welcome to compile it yourself.

 

Great job, it's working now, so thank you for the tips and the builds.